Handheld power tool, in particular handheld power saw

ABSTRACT

The invention relates to a handheld tool, in particular a handheld saw, with an electric drive motor ( 12 ), a serially switched gearbox ( 13 ), and a movement converter ( 14 ) that converts the driven movement of the gearbox ( 13 ) into an axial to-and-fro movement of a lifting element ( 15 ) for driving a tool ( 16 ), in particular a saw blade, inside a housing ( 11 ). The gearbox ( 13 ) and the movement converter ( 14 ) are combined into a gear unit ( 17 ). The gear unit ( 17 ) is within a robust, bending- and deformation-resistant gear housing ( 40 ), which is in turn inside the housing ( 11 ). The housing ( 11 ) is made of flexible plastic.

PRIOR ART

The invention is based on a handheld power tool, in particular ahandheld power saw, as generically defined by the preamble to claim 1.

A handheld power tool that can be bent longitudinally is known that hasan angular gear and a motion converter that converts the power takeoffrotary motion of the drive motor into an axially reciprocating workingmotion of the saw blade, and these parts are combined into a gear unit,forming a compact device. This handheld power tool can be supplied withpower via cords, from the utility grid. It is still quite bulky,however.

DISCLOSURE OF THE INVENTION

The handheld power tool of the invention, in particular the handheldpower saw, having the characteristics of claim 1 has the advantage thatit is designed to be small, handy, and above all both robust andlightweight. The flexible plastic housing is capable of absorbing forcesif the handheld power tool hits something or falls, without the risk ofdamage or destruction.

By the provisions in the other claims, advantageous refinements of andimprovements to the handheld power tool recited in claim 1 are possible.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in further detail in the ensuing descriptionin terms of exemplary embodiments shown in the drawings. Shown are:

FIG. 1, a schematic perspective view of a handheld power tool, embodiedas a handheld power saw, with a housing shell removed;

FIG. 2, a schematic side view of individual elements of the handheldpower tool, together with a portion of its gearbox;

FIG. 3, a schematic perspective exploded view of the elements shown inFIG. 2 of the handheld power tool;

FIG. 4, a schematic section through the handheld power tool in thedirection of the arrows IV-IV in FIG. 1, on a larger scale.

EMBODIMENTS OF THE INVENTION

In FIG. 1, an electric handheld power tool 10 is shown, which isdesigned as a small, handy, robust handheld power saw designedapproximately like a straight-back hand saw with an open handle. Thishandheld power tool 10, inside a housing 11, has an electric drive motor12, a gear 13 downstream of the drive motor 12, and a motion converter14. By means of the motion converter 14, the power takeoff rotary motionof the gear 13 is converted into an axially reciprocating working motionof a reciprocating element 15 for driving a tool 16, especially a sawblade. The gear 13 and the motion converter 14 form a drive train andare combined into a gear unit 17.

The gear 13 is embodied as an angular gear. It has a power takeoffpinion 18, which is press-fitted onto the motor shaft 19, and a crowngear wheel 20, with which the power takeoff pinion 18 is operationallyin engagement. By means of this gear 13, the power takeoff rpm of thedrive motor 12 is stepped down to a lesser rpm of the crown gear wheel20. The crown gear wheel 20 has a press-fitted-in bearing bolt 21, whichprotrudes to one side of the crown gear wheel 20 and is supported bymeans of at least one deep-groove bearing, and preferably by means oftwo axially adjacent deep-groove bearings 22, 23. In this way, the crowngear wheel 20 is floatingly supported. On the side diametricallyopposite the deep-groove bearings 22, 23, the crown gear wheel 20 has aneccentrically located, press-fitted-in bolt 24, which engages a sleeve25 on an end toward it of a connecting rod 26 of the motion converter14. Via the bolt 24, the power takeoff rotary motion of the crown gearwheel 20 is converted, by means of the connecting rod 26, into a linear,reciprocating motion with a suitable stroke length. The connecting rod26 is formed of two longitudinal struts 27, 28, parallel to one anotherand extending at a spacing from one another, which are connected in onepiece to one another on both ends via eyelets 29, 30 located there. Thesleeve 25 is received in the eyelet 29. In the region near the crowngear wheel 20, the connecting rod 26 is overlapped on both sides by pins31, 32 oriented transversely, and in particular approximatelyperpendicularly, to it, which serve to guide the connecting rod 26 onboth sides in the transverse direction.

The gear unit 17 formed of the above-described gear 13 and motionconverter 14 by combining them is located inside a robust gearbox 40that is resistant to bending and torsion. This gearbox 40 is in turnreceived in the housing 11. The gearbox 40 is formed in particular ofmetal, such as aluminum, and is in two parts. It comprises one moldedbody in the form of a housing shell 41 and a housing cap 42 that coversthe housing shell 41 and that is detachably connected to the housingshell 41 via fastening means 43, such as screws. The housing 11 isformed of two housing shells 33, 34, which are detachably connected toone another inside a mold parting plane 35 that is symmetrical to thehousing 11. This housing 11 advantageously comprises a flexiblematerial. This design with regard to material is possible because of thecompact structure and because of the fact that the gear unit 17 isreceived in the robust gearbox 40 that is resistant to bending andtorsion. The thus-designed flexible plastic housing 11 is capable ofabsorbing forces, for instance if the handheld power tool 10 falls. Thehandheld power tool 10 is in this way protected to a high degree againstdamage on falling, even if it falls from a great height.

A ribbed body 44, which is embodied as a heat sink and as a bending- andtorsion-resistant mount that is for an end plate 45 and which is in onepiece with the gearbox 40, is located on the gearbox 40, in particularon the housing shell 41, in the region below the motion converter 14.The end plate 45 is seated on a holder 46, which is secured to theribbed body 44. An electric switch 47, indicated only schematically, islocated laterally beside and approximately parallel to the gear unit 17,and its actuation member 48 is coupled to an actuator 45, such as atoggle, via a lever 50. An electronic monitoring device 51, alsoindicated only schematically, is likewise located laterally beside thegear unit 17, for instance approximately parallel to it, and is intendedto monitor the current consumption. Both the electric switch 47 and theelectronic monitoring device 51 are seated on the outside of the housingcap 42 that faces away from the housing shell 41. This arrangement againmakes a small, compact structure of the handheld power tool 10 possible.The location of the switch 47 and monitoring device 51 offsettransversely with respect to the approximately symmetrically extendingmold parting plane 35 means that the actuator 49, such as a toggle, istransversely offset relative to this mold parting plane 35 of bothhousing shells 33, 34, as can also be seen from the position of thethrough opening 52, indicated in FIG. 4, for the actuator 49.Particularly from FIG. 4, the floating support of the crown gear wheel20 by means of the two deep-groove bearings 22, 23 that are received inthe housing shell 41 also becomes clear. The gear 13 has a fan wheel 36,driven by it, which is located on the bearing bolt 21 of the crown gearwheel 20. By means of the fan wheel 36, which is provided on the drivemotor 12 in addition to the motor fan, heat dissipation from the gear 13and cooling, for instance of the electronic monitoring device 51, arepossible in a simple way. For removing heated air, conduits provided inthe usual way in the housing 11 and openings provided on the side of thehousing toward the end plate 45 are used, by way of which the waste airis carried away; the waste air simultaneously serves as blowing air forremoving particles, such as sawdust or chips, at the place beingmachined by the handheld power tool 10.

On the end facing away from the gearbox 40, the reciprocating element 15has a clamping system 53, shown only schematically, for interchangeablymounting a tool 16, such as a saw blade. The clamping system 53 isdesigned in the usual way and makes it possible to fasten a tool 16 bothin one position and in another position rotated 180° relative to it.This increases the accessibility to places that are hard to reach inworking with the handheld power tool 10, and thus the handheld powertool can be used even at poorly accessible places.

The reciprocating element 15 that can be driven to reciprocate by themotion converter 14 is embodied as a rod 55 that protrudes out of thegearbox 40. A slide bearing 56 is located in the gearbox 40, and in thisslide bearing the reciprocating element 15, in particular in the form ofthe rod 55, is supported and guided displaceably back and forth. Theslide bearing 56 is received nonrotatably between the housing shell 41and the housing cap 42 and is penetrated by the end toward it of thereciprocating element 15, in particular the rod 55. The location ismoreover selected such that guide means for guiding the reciprocatingelement 15 are provided that are operative between the slide bearing 56and the reciprocating element 15, in particular the rod 55. These guidemeans may be formed of a nonround and/or angular cross-sectional shapeof the reciprocating element 15 and of the bore, penetrated by it, ofthe slide bearing 56. In this way, torques introduced into thereciprocating element 15 as well are absorbed by the slide bearing 56.In the exemplary embodiment shown, the guide means between the slidebearing 56 and the reciprocating element 15 are formed of longitudinalguides 57, located on the slide bearing 56, which protrude from theslide bearing 56, and at least one connecting element 58, engaging thereciprocating element 15 in the region of the eyelet 30, by means ofwhich connecting element the motion converter 14 is connected on thepower takeoff side to the reciprocating element 15; by means of thelongitudinal guides 57, this connecting element 58 is supported andguided in the longitudinal and/or transverse direction. The at least oneconnecting element 58 for instance simply comprises a cross pin 59,which engages both the end of the connecting rod 26 remote from the gear13 and the end of the reciprocating element 15 toward the connecting rod26, and for instance transversely penetrates bores 60 provided in afork, located on the end of the reciprocating element 15, that receivesthe eyelet 30. The longitudinal guides 57 protrude from the slidebearing 56 in the direction toward the connecting rod 26 that extendsbetween them. The longitudinal guides 57 of the slide bearing 56 haveguide pins 61 on one side and 62 on the other side of the connecting rod26, which are approximately parallel to one another, and of which, threeguide pins may for instance be provided on each side. The connectingelement 58, in particular the cross pin 59, with respective endportions, protrudes on both sides out of the bores 60 of thereciprocating element 15 and is received with these two end portions onboth sides between two guide pins 61 on one side and 62 on the other;these two guide pins 61 and 62 extend in planes, approximately parallelto one another, that extend approximately parallel to the plane thatcontains the connecting rod 26. These two guide pins 61 and 62 on bothsides act similarly to respective longitudinal guide grooves for therespective end portion, located between them, of the connecting element58. The third guide pin 61 and 62 provided for each side, respectively,extends farther outward spaced apart from the respective aforementionedplane within which the respective pairs 61 and 62 of guide pins extend.This transverse spacing is approximately equivalent to the length of theconnecting element 58. It is thus attained that the connecting element58 rests, with the respective approximately frontal end on therespective guide pin 61 and 62 and is supported and guided not only inthe longitudinal direction but also in particular in the transversedirection as well. This design of the guide means is especially simpleand economical. As can be seen from FIG.

2, on the side of the slide bearing 56 that faces toward the clampingsystem 53, pins 63 analogous to the pins 31, 32 may be provided, betweenwhich the reciprocating rod 55 is additionally guided. The support asdescribed for the reciprocating element 15 including its guidance issimple and economical and makes fast, easy assembly possible.

The handheld power tool 10 is supplied with power by at least onebattery, preferably at least one rechargeable battery, which is shownonly schematically and identified by reference numeral 64. This at leastone rechargeable battery 64 is a lithium-ion (Li-ion) cell for supplyingthe drive motor 12.

The housing 11 has a first portion 65, acting as a handle part, and asecond portion 66, adjoining the first portion 65 in one piece andinclined at an obtuse angle to it. The at least one rechargeable battery64 and the electric drive motor 12 are both received in the firstportion 65, while the gearbox 40 with the gear unit 17 it contains arecontained in the second portion 66.

The handheld power tool 10 is small, lightweight, handy, and robust, andbecause of the power supply by means of at least one battery, inparticular a rechargeable battery 64, it is especially simple and easyto manipulate. Moreover, the handheld power tool 10 is highly safe inoperation and is also secure against damage from any impacts or fromfalling.

1.-20. (canceled)
 21. A handheld power tool comprising: (a) a housingformed of flexible plastic having a first portion, serving as a handlepart, and a second portion adjoining the first portion in one piece andat an obtuse angle; (b) an electric drive motor being received in thehousing; (c) a metal gearbox resistant to bending and torsion, the metalgearbox having two parts comprising a housing shell and a housing capthat covers the housing shell and that is detachably connected to thehousing shell, the metal gearbox being received in the second portion ofthe housing; (d) a gear connected to the electric drive motor; (e) amotion converter constructed and configured to convert power takeoffrotary motion of the gear into an axially reciprocating working motionof a reciprocating element for driving a tool, the reciprocating elementcomprising a rod protruding from the metal gearbox, with a clampingsystem located on one end for interchangeably mounting a tool; (f) agear unit that combines the gear and the motion convertor, the gear unitbeing received in the metal gearbox; (g) a slide bearing, in which thereciprocating element is supported and guided displaceably back andforth, the slide bearing being received in the gearbox; and (h) at leastone rechargeable battery for supplying the drive motor, the batterybeing at least partially received in the housing.
 22. A handheld powertool according to claim 21, wherein a reciprocating element and rod areformed separately and connected to each other by a pin.
 23. A handheldpower tool according to claim 21, wherein the tool is a saw blade.
 24. Ahandheld power tool according to claim 21 including: (a) an end plate;(b) wherein the clamping system is positioned between the end plate andthe gear box.
 25. A handheld power tool according to claim 21 including:(a) an electric switch and electric monitoring device.
 26. A handheldpower tool comprising: (a) a plastic housing having a handle part andanother portion adjoining the handle part; (b) a rechargeable batterypositioned received within the handle part; (c) a linearly reciprocatingtool; (d) an electric drive motor positioned in the housing and having arotatable motor shaft that rotates around an axis that extendsnon-parallel, non-colinear and non-perpendicular to a direction oflinear reciprocation of the tool; (e) a rotating gear positioned on themotor shaft; (f) a motion converter configured to convert rotary motionof the gear to axially linearly reciprocating motion of the tool, themotion converter comprising a connecting rod having first and secondopposite flat sides; and (g) a metal gear box secured to, and positionedwithin, the housing; (i) the motion converter being positioned in thegear box; (ii) the gear box including at least one gear wheel thereinhaving an eccentrically located projection; (iii) a sleeve which engagesan opening of the connecting rod and the eccentrically locatedprojection, the sleeve having a circular cross-section; (iv) the motorshaft projecting into the gear box from the motor; (v) a reciprocatingrod projecting outwardly from the gear box at an obtuse angle to themotor shaft, the reciprocating rod have a circular cross-section andbeing connected to the connecting rod; (vi) a slide bearing: (A)surrounding the reciprocating rod; and (B) positioned in the gear box;(vii) wherein the connecting rod of the motion converter is guided byelements adjacent to the flat sides of the connecting rod that limitrelative motion between the gear wheel and the motion converter in adirection transverse to that of the linear reciprocation direction ofthe tool.
 27. A handheld power tool according to claim 26, wherein thereciprocating rod and the connecting rod are formed separately andconnected to each other by a pin.
 28. A handheld power tool according toclaim 26, wherein the tool is a saw blade.
 29. A handheld power toolaccording to claim 26 including: (a) an end plate; and (b) a clampingsystem releaseably fastening the tool; the clamping system beingpositioned between the end plate and the gear box.
 30. A handheld powertool according to claim 26 including: (a) an electric switch andelectric monitoring device.